27 Mar
2005
27 Mar
'05
1:14 a.m.
On Sun, 27 Mar 2005 10:26:02 +1000, river <river at zip.com.au> wrote:
Hi,
I've got a few old SC/MP-II chips and I decided to try and do something with them.
It appears that only 2 of the chips actually work, but I've just proto-typed a small
system with 4K ROM, 4K RAM, an 8251 USART and an 8255 PPI. I got the
comms going yesterday and the PPI is fine. Excellent old vintage stuff.
Nice... I don't have any SC/MP chips, but I do have some INS8073s,
which should be an SC/MP chip, but with Tiny Basic in ROM. I have a
3"x5" vintage SBC with one, and a few loose chips. My board is an
MC-1N, for which I did eventually track down a copy of the manual last
year from the original vendor. I have permission to distribute it
from the copyright holder, even! Unfortunately, the
MC-1N seems to be
an obscure board... the rev I have is unusual now (there were
later
versions of the board with the same sort of I/O, but with a different
microprocessor).
For the record, the MC-1N has a 2K SRAM (6116), a clock/calendar chip,
a ROM socket, and an 8255 with all 3 ports brought out the front.
It's a nice little system that is just enough over minimal to be kinda
fun. Unfortuately, the 74S188 memory decode PROM doesn't allow for
more than 4 banks of 2K of SRAM. I _think_ a 16V8 GAL will work
there, if I lift the pullups (the 74S188 is O.C.) I don't have any
blank 74S188s, or I'd just blow one with a truth table that decodes
the max amount of RAM on a single select so it'd be trivial to use a
62256 (32K x 8)
I did get mine fired up with a terminal last year, and entered a few
BASIC programs to give it a whirl... It'd be possible to do a Star
Trek game on it (with more RAM), but I don't know if the BASIC could
handle a text adventure (most Tiny BASICs aren't excellent at string
maniupulation).
-ethan